A hernia is a protrusion of a tissue, structure, or part of an organ through the muscle tissue or the membrane by which it is normally contained. Inguinal hernias are one common type of hernia. In an inguinal hernia, a weakness in the abdominal wall grows into a hole, or defect. Tissue may protrude from the defect. Example hernias include umbilical hernias, in which intra-abdominal contents protrude through a weakness at the site of passage of the umbilical cord through the abdominal wall, and incisional hernias, which occur in an area of weakness caused by an incompletely-healed surgical wound. Those of skill in the art will appreciate that there are other types of hernias in addition to those specifically mentioned herein.
In order to treat a hernia, such as an inguinal hernia, a doctor may insert a specially designed patch or implantable prosthesis into an incision near the defect, e.g., near the naval. One example of such a medical procedure for implanting a prosthesis is totally extraperitoneal laparoscopic surgery. Implantable prostheses for repairing anatomical defects in tissue or muscle walls typically are designed to be larger than the defect so as to ensure adequate coverage and/or sufficient fixation of the prosthesis. During implantation, the prosthesis is folded and/or pushed through the incision. In order to allow the prosthesis to be positioned, it may include positioning straps, portions designed for suturing to the surrounding environment, and/or portions designed for fixation via in-growth of surrounding cells into the prosthesis. Once implanted, the prosthesis unfolds and is maneuvered into a suitable position. The positioned prosthesis is then secured by fixation. For example, fixation can include suturing the positioning straps to the margins of the defect, suturing a part of the body of the patch to the connective tissue, and allowing natural in-growth to occur. Excess material, such as excess material on the positioning strap, can be removed and the incision can be closed.
Some existing prostheses are manufactured to possess a flat, two dimensional shape. Such a shape is unsuitable for meeting the needs of repairing defects in some tissue or muscle walls. In particular, inguinal hernia repairs place stringent demands upon suitable shapes for implantable prostheses since the laparoscopic inguinal region is extremely complicated and includes many blood vessels, nerves, ligaments, and other anatomical components. Accordingly, the space in which the prosthesis is deployed contains many bumps, irregularities, and contours, which may be symmetrical or asymmetrical. Using flat, two dimensional prostheses thus places the burden of fitting the prosthesis to the anatomical region upon the surgeon. This results in additional required training for surgeons performing such operations. Furthermore, processes involving flat two dimensional prostheses generally are associated with a high learning curve, given the complexity of many anatomical regions, including the inguinal region. One of skill in the art can appreciate that such extended training and additional expertise generally increases the associated costs of such procedures, which is undesirable for patients and other consumers.
Existing attempts to solve the problem of providing a prosthesis that adequately accommodates the shape of a given anatomical region have included constructing preformed prostheses that independently assume a predetermined three-dimensional shape. Such preformed three-dimensional prostheses generally are much more effective at assuming the shape of an anatomical region, which thus reduces the required training, the length of the surgical procedure, and risk of error by the surgeon. Additionally, preformed three-dimensional prostheses can be associated with the benefit of not requiring suturing to ligaments or connective tissue, for example by using medical tacks. Rather, they can adequately enable in-growth fixation methods, which tend to reduce pain and/or discomfort in the patient, lower patient recovery time, shorten patient discharge time from the hospital, etc.
However, some existing preformed three-dimensional prostheses require additional support, such as for example, a rigidified peripheral edge at the perimeter of the body to independently maintain the predetermined three-dimensional shape. The rigidified peripheral edge can be formed, for example, by ultrasonic welding, making the perimeter substantially more rigid or rigidified relative to the remaining portions of the mesh prosthesis. The increased rigidity of the peripheral edge permits some degree of flexibility (e.g., to enable rolling) while also promoting the prosthesis' ability to assume the shape outlined by the rigidified peripheral edge. Prior designs require this rigidified peripheral edge to satisfy the intended function of independently assuming and reassuming a predetermined three-dimensional shape.
For prostheses having rigidified edges, trimming, cutting, removing, or otherwise altering portions of the rigidified peripheral edge or even the body itself are prohibited because to interrupt, break, or remove portions of the rigidified peripheral edge or perimeter significantly impacts the prosthesis' ability to independently assume the intended predetermined shape. The result is the undesirable consequence of the prosthesis losing its desired preformed three-dimensional contoured shape, and therefore becoming much more difficult to handle and position. In other words, for those prostheses that rely on the more rigid peripheral edge to maintain their shape, removal or interruption of portions of that edge dramatically affect the adaptability of such prostheses to a variety of different circumstances, anatomies, and/or procedures.
An additional shortcoming of existing prostheses is that, given the unique and asymmetrical shape of the internal region in the human body, known prostheses must be manufactured and sold as either a right prosthesis (oriented for the right side of the human body) or a left prosthesis (oriented for the left side of the human body). Accordingly, additional templates, molds, and other manufacturing machinery are required in order to build and sell both left orientation prostheses and right orientation prostheses. This requirement for duplicate manufacturing equipment places an additional financial burden on manufacturers. Furthermore, the requirement for both left and right prostheses requires hospitals to maintain a sufficient stock of both left prostheses and right prostheses, thereby increases inventory costs. In many cases, such added costs are simply passed on to the patient, resulting in a higher economic barrier for laparoscopic surgery, thus making such treatment methods less accessible or affordable to the general public.